The present invention, in some embodiments thereof, relates to therapy and, more particularly, but not exclusively, to a novel methodology for the treatment of hepatitis C virus (HCV) related diseases.
Infection by hepatitis C virus (HCV) is a compelling human medical problem. HCV is recognized as the causative agent for most cases of non-A, non-B hepatitis, with an estimated human sero-prevalence of 3% globally. Nearly four million individuals may be infected in the United States alone. Upon first exposure to HCV only about 20% of infected individuals develop acute clinical hepatitis while others appear to resolve the infection spontaneously. In almost 70% of instances, however, the virus establishes a chronic infection that persists for decades. This usually results in recurrent and progressively worsening liver inflammation, which often leads to more severe disease states such as cirrhosis and hepatocellular carcinoma.
The combination of a pegylated interferon (e.g., peg-IFN alpha-2a/b) and twice-daily oral doses of ribavirin, an anti-viral agent, is the current standard of care for the treatment of chronic HCV infection. Patients who will ultimately achieve a sustained virologic response to peg-IFN and ribavirin therapy usually develop a rapid decline in HCV-RNA levels after initiation of therapy, with levels becoming undetectable within 4-24 weeks. Liver enzyme levels become normal, and histologic findings improve markedly. With the above-mentioned combination therapy, approximately 75% to 80% of patients with HCV genotype 2 or 3 infection and 40% to 50% of those with genotype 1 infection achieve a sustained virologic response (SVR) [Sherman K. E., Clinical Need and Therapeutic Targets for New HCV Agents, in The Future of HCV: Small molecules in Development for Chronic Hepatitis C, Clinical Care Options LLC, 2007].
However, success rate of this combined therapy is limited as its outcome is highly dependent on the infecting HCV genotype. This treatment is effective in fewer than 50% of patients infected with HCV genotype 1 or 4, the most represented genotypes in Europe and USA. In many cases, non-response is related to host or viral factors that impair activation of the host's innate, interferon-driven immune response.
Others may achieve viral reduction during therapy but cannot tolerate full therapeutic doses or an adequate duration of treatment because of cytopenia, fatigue, or other adverse effects of treatment. Indeed, dose modifications for these reasons are required in 35% to 42% of treated patients, and approximately one third of these patients eventually discontinue treatment altogether. These dose reductions, temporary interruptions, and aborted treatment courses reduce the chance of achieving SVR.
Finally, the combination of peg-IFN and ribavirin is contraindicated altogether in many patients who are in need of anti-HCV therapy. Contraindications for therapy include severe cytopenia, hepatic decompensation, renal insufficiency, poorly controlled autoimmune disease, severe cardiopulmonary disease, and active psychological problems. [Davis G. L., Investigational Small-Molecule Agents for the Treatment of Chronic Hepatitis C, in The Future of HCV: Small molecules in Development for Chronic Hepatitis C, Clinical Care Options LLC, 2007].
Alternative therapies for the treatment of HCV related diseases have been developed. Such therapies are disclosed, for example, in U.S. Pat. Nos. 6,849,254; 7,115,578; 7,410,979; 7,671,017 discloses the use of cyclosporine and pegylated interferon for treating HCV.
One of the current approaches for treating HCV utilizes HCV protease inhibitors. See, for example, Chen K X, Njoroge F G. A review of HCV protease inhibitors. Curr Opin Investig Drugs. 2009 8, 821-37; 2: Garg G, Kar P. Management of HCV infection: current issues and future options. Trop Gastroenterol. 2009 30, 11-8; 3: Pereira A A, Jacobson I M. New and experimental therapies for HCV. Nat Rev Gastroenterol Hepatol. 2009 7, 403-11.
HCV is a positive-stranded RNA virus which has been classified as a separate genus in the Flaviviridae family. All members of the Flaviviridae family have enveloped virions that contain a positive stranded RNA genome encoding all known virus-specific proteins via translation of a single, uninterrupted, open reading frame. The single strand HCV RNA genome is approximately 9500 nucleotides in length and has a single open reading frame (ORF) encoding a single large polyprotein of about 3,000 amino acids. In infected cells, this polyprotein is cleaved at multiple sites by cellular and viral proteases to produce the structural and non-structural (NS) proteins. In the case of HCV, the generation of mature non-structural proteins (NS2, NS3, NS4A, NS4B, NS5A, and NS5B) is effected by two viral proteases. The first one cleaves at the NS2-NS3 junction; the second one is a serine protease contained within the N-terminal region of NS3 and mediates all the subsequent cleavages downstream of NS3, both in cis, at the NS3-NS4A cleavage site, and in trans, for the remaining NS4A-NS4B, NS4B-NS5A, NS5A-NS5B sites. The NS4A protein appears to serve multiple functions, acting as a co-factor for the NS3 protease and possibly assisting in the membrane localization of NS3 and other viral replicase components. The NS3 protein also exhibits nucleoside triphosphatase and RNA helicase activities. NS5B is a RNA-dependent RNA polymerase that is involved in the replication of HCV.
The NS3 serine protease, located in the N-terminal domain of the NS3 protein, mediates all of the subsequent cleavage events downstream in the polyprotein. Because of its role, the NS3 serine protease is an ideal drug target. Hexapeptides as well as tripeptides show varying degrees of inhibition of NS3 serine protease are described, for example, in U.S. patent applications having publication Nos. U.S. 2005/0020503, U.S. 2004/0229818, and U.S. 2004/00229776. Macrocyclic compounds that exhibit anti-HCV activity have been disclosed, for example, in WO 20061119061, WO 2007/015855 and WO 2007/016441 (all by Merck & Co., Inc.).
The discovery of novel antiviral strategies to selectively inhibit HCV replication has long been hindered by the lack of convenient cell culture models for the propagation of HCV. This hurdle has been overcome first with the establishment of the HCV replicon system in 1999 (Bartenschlager, R., Nat. Rev. Drug Discov. 2002, 1, 911-916 and Bartenschlager, R., J. Hepatol. 2005, 43, 210-216) and, in 2005, with the development of robust HCV cell culture models (Wakita, T., et al., Nat. Med. 2005, 11, 791-6; Zhong, J., et al., Proc. Natl. Acad. Sci. U.S.A. 2005, 102, 9294-9; Lindenbach, B. D., et al., Science 2005, 309, 623-6).
Chloroquine is a well known lysosomotropic agent, currently attracting many hopes in terms of antiviral therapy as well as in antitumoral effect because of its pH-dependent inhibiting action on the degradation of cargo delivered to the lysosome, thus effectively disabling this final step of the autophagy pathway.
Hydroxychloroquine (HCQ) is a chemical derivative of chloroquine (CQ) which features a hydroxylethyl group instead of an ethyl group.

HCQ has been classified as an effective anti-malarial medication, and has shown efficacy in treating systemic lupus erythematosus as well as rheumatoid arthritis and Sjögren's Syndrome. While HCQ has been known for some time to increase lysosomal pH in antigen presenting cells, its mechanism of action in inflammatory conditions has been only recently elucidated and involves blocking the activation of toll-like receptors on plasmacytoid dendritic cells (PDCs).
A direct comparison of the therapeutic effect of CQ and HCQ is quite difficult but it has been suggested that hydroxychloroquine was one-half to two-thirds as effective as chloroquine in treating rheumatologic diseases and one-half as toxic [Scherbel A L et al., Cleve Clin Q, 1958, 25:95]. Since chloroquine appears to be much more retinotoxic frequent use of hydroxychloroquine is increasing [Rynes R. I., British Journal of Rheumatology, 1997; 36:799-805].
Chloroquine and derivatives thereof such as HCQ have been discussed in the context of HCV therapy in, for example, Chandramohan M. et al. [Indian J Pharm Sci 2006; 68:538-40]; Freiberg et al. [Journal of General Virology (2010), 91, 765-772]; Zuckerman et al. [BioDrugs 2001; 15(9), pp. 574-584]; Mizui et al. [J. Gastroenterol. 2010 February; 45(2):195-203. Epub 2009 Sep. 17].
Additional background art includes WO 2012/061248 and WO 2011/161644.